The present invention relates generally to a socket for a module, and more particularly to a socket of improved connection reliability.
Conventionally, sockets have been used to mount camera modules, which integrates an image pickup device such as a CCD (Charge Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor) image sensor, or the like, and an optical element such as a lens, on a substrate of a small electronic device such as a cellular telephone, a PDA (Personal Digital Assistant), or the like. One such structure is described in Japanese Patent Application Laid-Open (Kokai) Publication No. 2003-91685).
FIG. 10 is a cross-sectional view of such a conventional camera module socket.
801 denotes the socket housing for a module, while 802 denotes the camera module, which is received in the socket housing 801. Also, two sets of locking devices 804 are provided on the inner surfaces of facing sidewalls of the socket housing 801 and engage locking surfaces 810 formed on the shoulder portions of the camera module 802 for locking the camera module 802 in place.
Each set of locking devices 804 include locking elements 805 and 806 having different heights. This is an arrangement to deal with the fact that a small module 802a having a relatively small outer dimension and a large module 802b having a relatively large outer dimension exist in the same kind of camera modules 802 due to dimensional errors in manufacturing. In the case of the small module 802a, the locking element 806 located at a lower position engages the locking surface 810, and in the case of the large module 802b, the locking element 805 located at a higher position engages the locking surface 810.
In addition, connection terminals 807 are provided on the bottom of the socket and protrude upward from the bottom 808 due to their spring property in order to contact members formed on the bottom of the camera module 802. Then, the height of protrusion of the connection terminal 807 must be lesser for the small module 802a, larger for the large module 802b. 
However, in the conventional socket for a module, two locking positions are provided by means of locking elements 805 and 806 which deal with variations of the contact force of the connection terminal 807 due to a change in the height of protrusion of the connection terminal 807 caused by dimensional errors in manufacturing of the modules 802. In order to provide a plurality of locking positions in this way, the shape of the locking elements 805 and 806 and the structure of the module socket are complicated. A structure to obtain more stable contact is not sufficiently considered. Therefore, the contacting state between the connection terminal 807 and the contact member formed on the bottom of the camera module 802 becomes unstable. Also, the contact between the connection terminal 807 and the contact member formed on the bottom of the module 802 cannot be reliably maintained when the socket receives an impact from the outside due to any cause which may occur.